The invention is in the field of articulated, wheeled vehicles, particularly two-wheeled trailers and a towing package therefor by which the trailer is steerable in both the forward and reverse modes of travel. More particularly, the present invention relates to a single axle trailer and a novel hydraulic steering package having means to detect and respond to conditions of operation of the trailer such as direction of travel, articulation angle, wheel steering angle, speed of travel, and their interrelationships.
It is an object of the invention to convert the motion of articulation of the trailer relative to a towing vehicle into steering for the trailer wheels by means of controls which enable automatic steering in reverse and forward so as to attain ideal relationships of wheel steering angle to articulation angle upon changing directions of travel.
Additionally, it is an object of the invention to provide a steering package which senses the speed of forward travel and, above a specifiable speed, locks the wheels of the trailer in a straight ahead, nonsteering condition while still allowing articulation about the hitch ball. This provides the advantage of increasing the stability of the trailer at high speeds, which may be required for some load/trailer geometry combinations. It is a further object of the invention to provide for automatic resumption of the steering of the wheels upon sensing a reduction of the speed below another specifiable speed.
Also, it is an object of one embodiment of the invention to provide a steering package for the trailer which detects any articulation angle upon transition of the travel mode from forward-to-reverse or reverse-to-forward and further compensates the steering so as to avoid "crabbing" of the trailer relative to the towing vehicle.
Still further, it is an object of the invention to constantly monitor and compare the articulation and wheel steering angles as percentages of their respective ranges of angulation in order to detect any leaks in a hydraulic circuit which interconnects means for detecting the articulation and adjusting the steering in response to such detection.
It is another object of this invention to provide such a steering package which is adapted to the SAE standard ball hitch, so that the trailer is easily mountable and dismountable from the tow hitch in the typical manner.
Simply stated, it is an object of this invention to remove the major impediment to casual use of small trailers, namely, the difficulty of maneuvering them when backing-up.